The present invention relates to a recording apparatus such as the laser printer.
In a laser printer as shown in FIG. 1, for example, laser beam L generated by a laser generator (not shown) is scanned by rotating polygon mirror 2. This scanned laser beam L is introduced onto photosensitive drum 12, via first f.theta. lens 4, first mirror 6, second mirror 8, and second f.theta. lens 10, whereby the surface of drum 12 is exposed. Since the surface of photosensitive drum 12 has been previously been charged by charger 14, an electrostatic latent image is formed thereon. In FIG. 1, numeral 16 denotes a means for developing the electrostatic latent image to form a developed image, 18 a charger for transferring the developed image onto a sheet of paper, 20 a means for fixing the transferred image on the sheet of paper, 22 a tray for receiving the sheet of paper on which the image has been fixed, 24 a cleaning means for removing the developing agent remaining on photosensitive drum 12 after image transfer, 26 a lamp for removing electricity from the surface of photosensitive drum 12 after the cleaning process has been completed, 28 a cassette for storing paper sheets which are to be supplied between photosensitive drum 12 and transfer charger 18, and 30 a guide for supplying the paper sheets manually.
First f.theta. lens 4 is spherical, while second f.theta. lens 10 is a toric. Either the light-entering face or the light-emitting face of second lens 10 can be formed having a toric face, this face being formed by rotating an arc. When the scanning angle of rotating polygon mirror 2 becomes greater than .+-.30.degree. in this case, the property of the f.theta. lens cannot be satisfied. The scanning angle which can meet the property of the f.theta. lens accordingly becomes small. It is therefore needed that the optical path extending from rotating polygon mirror 2 to photosensitive drum 12 is made long for the purpose of making the scanning width large on photosensitive drum 12. The apparatus thus becomes large in size and expensive in cost.